Low-fat diets decrease testosterone levels in men, Study says

The study is published in the Journal of Steroid Biochemistry and Molecular Biology.

Higher endogenous testosterone levels are associated with reduced chronic disease risk and mortality. Since the mid-20th century, there have been significant changes in dietary patterns, and men's testosterone levels have declined in western countries. Cross-sectional studies show inconsistent associations between fat intake and testosterone in men.

Therefore, Joseph Whittaker and Kexin Wu from the School of Allied Health and Community, University of Worcester, Henwick Grove, United Kingdom carried out the present study with the objective to study the association between low-fat diets and testosterone in men.

Studies eligible for inclusion were intervention studies, with minimal confounding variables, comparing the effect of low-fat vs high-fat diets on men's sex hormones. 9 databases were searched from their inception yielding 6 eligible studies, with a total of 206 participants.

Random effects meta-analyses were performed using Cochrane's Review Manager software. Cochrane's risk of bias tool was used for quality assessment.

The results showed that -

a. There were significant decreases in sex hormones on low-fat vs high-fat diets. b. Standardised mean differences with 95 % confidence intervals (CI) for outcomes were: total testosterone [−0.38 (95 % CI −0.75 to −0.01) P = 0.04]; free testosterone [−0.37 (95 % CI −0.63 to −0.11) P = 0.005]; urinary testosterone [−0.38 (CI 95 % −0.66 to −0.09) P = 0.009]; and dihydrotestosterone [−0.3 (CI 95 % −0.56 to −0.03) P = 0.03].

c. There were no significant differences for luteinising hormone or sex hormone binding globulin.

d. Subgroup analysis for total testosterone, European and North American men, showed a stronger effect [−0.52 (95 % CI −0.75 to −0.3) P < 0.001].

Hence, it was concluded that "Low-fat diets appear to decrease testosterone levels in men, but further randomised controlled trials are needed to confirm this effect. Men with European ancestry may experience a greater decrease in testosterone, in response to a low-fat diet."